I'm going to add a good surprise here. I've been using adaptive cruise control with steering assist and I'm getting the hang of it. It performs quite well overall on the freeway.
On straightaways and very gentle curves with clear lane markings it's good enough that you can temporarily take your hands off the wheel. If the curves get tighter it wobbles but it does a good enough job that all you have to do is help it a bit by actively steering to stay in the middle of the lane and not drift too much.
In more challenging situations it quits and picks back up fairly often. But that's ok because I have hands on wheel and paying attention. Given that the system is has its (documented) limitations, the silent quitting and picking back up is a feature, not a bug. I wouldn't want it to dingdingding all the time, and even in these situations it performs well enough that it makes for much more relaxed driving. Combined with the adaptive cruise control it's significantly stress-reducing.